CAD Design and Drafting

The Problem Being Solved

In CAD drafting workflows, engineers often need to quickly convert design intentions into standard drawings. Traditional methods involve manual operation of AutoCAD or other software, writing commands, setting layers, and adding annotations, which is not only time-consuming but also error-prone. This becomes especially inefficient when teams lack professional CAD licenses, face complex environment configurations, or when engineers do not have the software installed. This skill specifically addresses this problem: it allows users to describe engineering requirements in a single natural language sentence and automatically delivers editable, printable CAD drawings, without needing to write JSON, select backends, or memorize complex commands.

Core Workflow

The skill achieves automated drafting through the following key steps, ensuring a complete flow from requirement to delivery:

• Freezing User Requirements: It parses natural language input to extract parameters such as purpose, units, dimensions, views/sheets, annotations, materials, output formats, and prohibited assumptions. For example, when a user says, "Draw a 120 × 80 × 6 mm Q235 mounting plate with four Ø8 through holes," the skill automatically identifies these engineering parameters and organizes them into structured intent.

• Environment Detection and Installation: It prioritizes using the user-provided cad-cli executable or one in PATH. If not found, it automatically installs cad-cli 1.5.16 from the SkillHub public interface, verifying version, byte size, SHA-256, and archive path, then returns the absolute executable path. Installation requires no login or API Key, and cad-cli --version is run to confirm the version.

• Automatic Backend Selection: It lets the CLI detect the environment and choose a backend based on capabilities: matching AutoCAD → supported ZWCAD → embedded portable backend → configured cloud execution backend. Users do not need to manually select the execution method. Common 2D primitives like arcs, splines, dimensions, layers, hatches, title blocks, etc., when capabilities fully cover, use the portable backend to output editable DWG/DXF without requiring AutoCAD installation.

• CLI Planning and Execution: Requests are constructed per the Agent execution contract and invoked via standard input. For general tasks, the generate command with --progress-jsonl monitors stage events and heartbeats; for factory layout tasks, it uses factoryLayoutIntent v2 asset families, selecting assetId and variantId from assets shared by CAD and SOLIDWORKS, and declaring atomic instance relationships to complete physical validation, clearance placement, connector吸附, and orthogonal obstacle avoidance routing. Only stdout JSON results are recognized.

• Quality Acceptance and Delivery: The CLI completes a single loop of "generate DWG/DXF → re-open and re-read → rule validation → PDF rendering check → bounded deterministic correction → re-read". It verifies user-specified graphic counts, dimensions, views, sheet counts, title blocks, BOMs, annotations, and output files. Upon delivery, it lists each DWG, DXF, PDF file, explains the actual drafting path used (e.g., portable backend or AutoCAD), and invites user confirmation of annotations, title block, and layout.

Applicability Boundaries and Considerations

The skill has clear scopes and limitations that engineers should note:

• Does Not Replace Professional Tools: It focuses on 2D drafting and does not support 3D solid modeling, finite element analysis, structural safety review, or sign-off. 3D design and analysis tasks should be handled by appropriate professional tools and engineers.

• Depends on CLI and Backend: Drafting relies on cad-cli and backend execution. If backend capabilities do not cover a task (e.g., full CAD capabilities needed but not available locally), it returns a structured gap without silently switching or faking success with simplified geometry.

• User Confirmation on Key Points: It only asks users for information that would change engineering results, such as missing dimensions, interfaces, standard versions, materials, tolerances, or safety conditions. On first use or when no specific task is given, it reads getting-started examples without blocking clear tasks.

• No Automatic Retry: Failures due to dependencies, versions, licenses, file locks, etc., are not automatically retried. It only retries when the user changes intent or the receipt indicates correctable input, keeping original engineering requirements unchanged. When generation results are uncertain, it does not automatically resend, as requests may have been billed.

• Files and Formats: It outputs editable DWG/DXF and multi-sheet PDFs. Portable PDFs retain curves, dimension extension lines, and arrows, and perform deterministic corrections on paper orientation, size, and text readability; missing fonts or cropping are explicitly failed, not faked as success.

In this way, the skill provides engineers with an automated bridge from natural language to standard CAD drawings while clearly defining boundaries to ensure reliability and professionalism.